1. Field of the Invention
An aspect of the present invention relates to a band type filter which is mounted, for example, on a tubular member such as a control valve for controlling the flow of oil inside an internal combustion engine of an automobile for preventing the inclusion of extraneous materials into the component.
2. Description of the Related Art
For example, many control valves are used in an internal combustion engine and an automatic transmission of an automobile for controlling the pressure of fluid such as oil and switching flow paths of the oil. When extraneous materials in oil are included in such a control valve, there is caused a fear that a proper operation of the control valve is disturbed. Because of this, a filter is mounted in such a member as a control valve through which oil flows for capturing extraneous materials in the fluid to prevent the inclusion of the extraneous materials into the control valve.
As a filter of this type, JP-2007-791-A discloses a control valve filter having a substantially annular frame element, a filtering member provided on the frame element and elastic engagement portions provided at both distal ends of the frame element and adapted to be brought into engagement with each other, wherein the frame element is mounted in a circumferential groove formed on an outer circumferential surface of a control valve main body for filtering a fluid flowing into ports opened in the circumferential groove with the filtering member.
Incidentally, the frame element of JP-2007-791-A on which the filtering member is provided is formed into the substantially annular shape, that is, a shape which surrounds the circumferential groove formed on the outer circumferential surface of the control valve. Because of this, for example, in the case of a control valve having a cylindrically tubular shape, a frame element (filter) having a circularly annular shape is necessary, while in the case of a control having an angularly tubular shape, a frame element (filter) having an angularly annular shape is necessary. Thus, frame elements matching the shapes of control valves must be used respectively or filters cannot be mounted on control valves, leading to a problem that poorly versatile filters eventually increase the production costs of an automobile, for example.
In addition, a frame element such as that described above is formed by injecting a synthetic resin into a cavity of a mold, and in the event that a frame element has the substantially annular shape which surrounds the outer circumference of the control valve, when the molded frame element is attempted to be removed from a pair of split molds, since the frame element is caught by the molds, the frame element cannot be removed from such a pair of split molds. Because of this, to mold the frame element described above, a mold provided with a sliding mechanism is required, leading to a drawback that costs for molding machines and molds are increased. In addition, with a mold having a complex construction to include the sliding mechanism, it is difficult to mold a number of frame elements at the same time, and only one frame element has to be molded at one time, leading to a problem that mass production cannot be expected.